Rotary, tubular impeller

ABSTRACT

A helicopter, autogyro, windmill or other impeller, comprising blades, optionally resilient or substantially rigid, each having: a tip free of attachment to other blades and urged into extended position by centrifugal force; and blade-strengthening tubular members containing gaseous material, imbedded in foam plastic. Each tubular member may be: an elongated flat-ended tube or can; or a row of end-joined tubes or cans. The gaseous material may be: helium, air or other gas (preferably strongly pressurized); gas-cell-containing foam plastic; or other, gas-containing material. The preferably hinged form of the impeller comprises at least one aligned pair of blades (two pairs being shown), each pair comprising inflated tubes extending from one end of the blades to the other end, having walls of: thin ductile or resilient metal (preferably lead), optionally coated with rubberimpregnated fabric or with rubber or other resilient plastic; plastic-coated fabric; resilient plastic; glass; or the like. Each tube has flattened and sealed ends and a flattened middle portion clamped by a plate to the impeller shaft, providing flexible, integral hinges at this middle portion permitting tilting of the blades, balancing centrifugal and aerodynamic forces on each side of the rotary shaft. The flat-ended tubes are preferably flanked by blade-stiffening tubular members preferably rows of metal cans, end-joined by preferably resilient plastic. When the tubular members are of plastic or glass they optionally may be blow-molded or centrifugally molded.

Moore July 3, 1973 ROTARY, TUBULAR IMPELLER 57 ABSTRACT [76] I v ntor;Alvin Edward Moore, 916 B h A helicopter, autogyro, windmill or otherimpeller, B l a d; w fifid; M'i' f39576 comprising blades, optionallyresilient or substantially rigid, each having: a tip free of attachmentto other [22] Flled: 1971 blades and urged into extended position bycentrifugal 211 N 107,101 force; and blade-strengthening tubular memberscontaining gaseous material, imbedded in foam plastic. RelatedApplication Data Each tubular member may be: an elongated flat-endedContinuation-impart 0f 1 y 6, tube or can; or a row of end-joined tubesor cans. The 1969 3,559,923- gaseous material may be: helium, air orother gas (preferably strongly pressurized); gas-cell-containing foam[52] US. Cl. 416/84, 416/230 plastic; or other, gas comaining materiaLThe prefera [51] Int. Cl. B64c 27/46 bly hinged f of the impellercomprises at least one [58] Fleld of Search 416/229, 226, 230, alignedpair of blades (two pairs being show"), each 416/233, 241 A, 224, 84, 88pair comprising inflated tubes extending from one end of the blades tothe other end, having walls of: thin duc- [56] References Cited tile orresilient metal (preferably lead), optionally UNITED STATES PATENTScoated with rubber-impregnated fabric or with rubber 2,172,333 9/1939Theodorsen et al 416/88 or other resilient P Plastic-coated fabric;resilient 1,360,596 11 1920 St. John 416 84 plastic; glass; or the like.Each tube has flattened and 2,226,978 12/1940 Pescara 416/84 UX sealedends and a flattened middle portion clamped by 2,616,509 11/1952 Thomas4l6/84 a plate to the impeller shaft, providing flexible, integral2,728,702 12/1955 sifmn 416/229 X hinges at this middle portionpermitting tilting of the 3,028,292 4/1962 HlnClS 416/226 X blades,balancing centrifugal and dy i forces 3O65799 11/1962 McCarty 416/88 Xon each side of the rotary shaft. The flat-ended tubes 3,068,565 12/1962Kmg et al.... 416/229 UX 3,229,935 l/l966 Bellanca 416/233 x arePreferably flanked by blade'st'ffemng l 3,321,019 5/1967 Dmitroffetal........ 416/230 hers Preferably metal cans end'lmned by 3,554,664 11971 Cheeseman et al 416/230 x Preferably resilient p when the tubularmembers are of plastic or glass they optionally may be blow- PrimaryExaminer-Everette A. Powell, Jr. molded centrifugany molded- 27 Claims,19 Drawing Figures PAIENTEDJIR am 3743440 AL\/|N EDWARD MOORE.

INVENTOR.

ATTORNEY.

PATENTED Jul 3 I873 Sim-2N2 FIG. 10

FIG.11

FIG. 12

FlG. 19

E. R O O M D R A W D E N V m INVENTOR- ATTO R N EY.

ROTARY, TUBULAR IMPELLER This application is a continuation-in-part ofprior, copending application Ser. No. 822,199, filed on May 6, 1969 (US.Pat. No. 3,559,923), comprising parts that were divided from thatapplication.

Excepting slight drawing changes, FIGS. 7, 8, 9, ll, 16, 17 and 19 are,respectively, practically the same as FIGS. 12,13,14, 6, 2, 11 and 15 ofapplication Ser. No. 822,199; FIG. 15 is the same as the forward,impeller part of FIG. 1 of the prior application; and FIGS. and 18 aresomewhat similar to FIGS. 8 and 11 of the former application.

The present invention is of an aircraft lifting propeller (or otherimpeller usable in transport craft or windmills) that is nearlywreckage-proof. It is made in view of the need to reduce the complexity,expense and noise of present-day helicopters, and is especially intendedfor use in helicopters or autogyros. The autogyro, invented by de laCierva and developed in the late 1920s and l930s, is a simpler andcheaper-to-build machine than the currently-known helicopter. Its defectof heavy drag per pound of load can be alleviated by use of thelight-weight body construction and balloon means presented by thisinventor in the said application Ser. No. 822,199 and in others of hisapplications and patents. Such use makes possible an efficientsmall-diameter autogyro impeller having little drag but sufficientlifting force to lift a slightly heavier than air craft off the land orwater. A balloon means aiding in attaining such lightness is shown forinstance in FIG. at 1; preferably it is larger than here illustratedhaving sufficient buoyancy to lift a substantial portion of the weightof the light-weight-framed, load-carrying body 2 from a stationaryposition. The impeller 3 may be of an autogyro but preferably it, aswell as each of the impellers of FIGS. 1 to 9, is a lifting propeller ofa light-weight helicopter, optionally rotated by an auxiliary electricor fluid motor or gas turbine, and optionally in combination with atraction propeller, 4.

Some objects of this invention are to provide: (1) a light-weight butstrong propeller assembly having a shaft and blades hinged with respectto the shaft, comprising tubular members containing gaseous material andplastic surrounding the tubular members; (2) such an impeller having apair of aligned blades, each comprising a plurality of juxtaposed,inflated, resilient tubular members extending from end to end of thepair, having integrally hinged central portions that are flattene d andclamped by an element on an end of the shaft; (3) an impeller as inobject l having an aligned pair of blades, each comprising a pluralityof juxtaposed, inflated, resilient tubular members, extending froma'flattened and sealed, central-hub, hinged portion to a flattened andsealed free end, unattached to other structure; (4) an impeller as inobject (I) in which the tubular members comprise a plurality of cans;(5) an impeller as in object (4) in which the cans have corrugatedwalls; and (6) an impeller as in object (4) in which the tubular memberscomprise rows of end-joined cans.

Other objects of the invention will be apparent in the followingspecification and claims and the accompanying drawings.

In these drawings:

FIG. 1 is a plan view of one form of the invented impeller, partlybroken away to expose its internal structure along a plane normal to theimpellers axis;

FIG. 2 is a sectional view from the plane indicated by the arrows 2-2 ofFIG. 1;

FIG. 3 is a sectional view from the plane 3-3 of FIG. 1, showing one ofthe optional types of airfoil body material;

FIG. 4 is a sectional view from the plane 4-4 of FIG. 1, showing anotherof the optional types of airfoil body material;

FIG. 5 is a plan view on a scale reduced from that of FIG. 1 of animpeller of the general type of FIGS. 1 to 4, in which the integralhinges of each aligned pair of the blades are not at the right angle tothe axis of the blades;

FIG. 6 is a sectional detail view, from a plane comparable to thatindicated at 6-6 in FIG. 5, of the clamping plate used to flatten themiddle parts of the blades;

FIG. 7 is a plan view, partly broken away and partly in section from aplane normal to the axis of the propeller, showing a second form of theimpeller;

FIG. 8 is a' detail view, in section from a plane comparable to thatindicated by the arrows 8-8 of FIG. 7, showing an optional form of thehub and assembled set of impeller blades, comprising a curved spinnerdisk in advance of the blades, and not having the optional bracing bars18;

FIG. 9 is a view in section from a plane normal to the axis of analigned pair of the blades of FIGS. 7 and 8;

FIG. 10 is a detail sectional view of a row of endjoined cans from aplane parallel to the axis of a blade that comprises rows of cans astubular members;

FIG. 11 is a detail sectional view of an alternative type of row' ofcans;

FIGS. 12 and 14 are detail sectional views of tubular members comprisingcorrugated cans or tubes;

FIG. 13 is a detail plan view, partly broken away, of another form ofcorrugated tubular member;

FIG. 15 is a plan view, partly broken away, of a third form of theinvented tubular impeller, having metallic hinges;

FIG. 16 is a sectional view from the plane 16-16 of FIG. 15;

FIG. 17 is a detail view, in section from the plane indicated by thelines 17-17 of FIG. 15, showing an optional type of the hinges andblades;

FIG. 18 is a sectional view'similar to FIG. 17, showing a tubularimpeller that does not have metallic or flattened-tube hinges; and

FIG. 19 is a detail view in section from a plane comparable to thatindicated by the arrows 19-19 of FIG. 17, on a reduced scale, showingone form of joint between flattened-end tubular members and hinge platesof the type of FIG. 17 or hub portions of the type of FIG. 18.

With reference to the drawings, the invented impeller basicallycomprises: a rotary. shaft 5,5A,5B, 5C, an optional but preferable hub(the hub plate 6 in FIGS. 1 and 4; 6-16-18 in FIG. 7; 60 in FIGS. 17 and18).; blades (7 in FIG. 1, 66 in FIG. 17); aerodynamicallyshaped airfoilskins optionally the outer surfaces of the airfoil hotly material, orrubber or epoxy coating, or other envelopes of molded, dense, resilientplastic, or fabric impregnated with rubber or other flexible plastic (8in FIGS. 1 to 4 and 7, in FIGS. 17 and 18);

tubular members of thin metal, plastic, fabric-andplastic, glass, or thelike (9, 9', 10 and 12 in FIGS. 1 to 4; 40 and 41 in FIGS. 7 to 9; 68 inFIGS. 17 and 18; and in FIG. 19); gaseous material in the tubularmembers;

and airfoil-body material between the tubular members and skin,preferably surrounding all or nearly all of the tubular elements in eachblade (14 in FIGS. 1 to 4, 9 and The following four briefly describedforms of the invention are illustrated in the drawings: (1) The speciesof FIGS. 1 to 6 (considered with FIGS. 10 to 14) comprises fourelongated, inflated tubes (9) of flexible material, each of which isflattened at the hub between tube-clamping hub plates 6 and (or 20'),forming a long-lasting integral hinge between aligned, integrallyjoinedblade tubes. These integral tubes, which extend thru the hub part fromone blade tip to the tip of the opposite blade, thus are hinge tubes.Their walls are of strong and highly ductile or resilient materialpreferably ductile metal'(for example, lead) preferably thin lead,sheathed in strong fabric. They are preferably so highly pressurizedwith air or other gas or pressurized foam plastic that they yield(safely) only under such a major shock as would break or badly damage apresently common type autogyro or other impeller blade. This inventionform comprises auxiliary, plasticenveloped, blade stiffening andstrengthening tubular members (10 or 12) which stop short of the hub andthus do not interfere with hinging of the flexible, flattened-tubehinges. Their main purpose is to fill out and strengtheningly form themajor portion of each airfoil blade, with a minimum of weight. Beingpreferably stiffly flexible (for example, of bamboo or rubberjointedcans), in major shock they safely follow the movements of theirconnected impeller-hinge tubes 9. In FIG. 5, the flat, integral-tubehinges of the tubes 9 are exampled as optionally at oblique angles tothe axis of each pair of aligned blades. (2) The invention species ofFIGS. 7 and 8 differs from the above species (I) in having, in eachblade: only two inflated flat-hingeproviding tubes (40 and 41), havingunequal diameters and tube-flattened, hub-clamped hinge parts that arenot integral with opposite tubes; and in having bladestiffening,light-weight, tubular filler members 10 (FIG. 9) that are arrangeddifferently from the filler elements 10 and 12 of FIGS. 1 to 6. (3) Inthe invention form of FIG. 19 (considered with FIGS. l5, l6 and 2), eachblade has a plurality of stiffly-flexible, light-weight,strength-providing, flat-ended, inflated tubes of different diameters.These blade tubes are similar to the hinge tubes of FIGS. 1 to 9 exceptthat they are not integral with blade tubes on opposite sides of thehub. They are hinged to the hub by the pivot-bearing type of hinge shownat 62 and 62 in FIGS. 19 and 17 and in FIG. 15. (4) The inventionspecies of FIGS. 17 and 18 (considered with FIGS. 15, 16 and 9 andoptionally with FIGS. 10 to 14) comprises blades having rows of cansthat are joined at their ends by preferably resilient plastic, and areoptionally connected to the hub by the hinge of FIG. 17 or the joint ofFIG. 18. In each of the currently preferred forms of the invention(shown in FIGS. 1 to 9) the rotor blades are stiffly resilient becauseof the inflated ductile or resilient tubes 9 and the preferablyresilient auxiliary tubular members 10 and 12 which preferably comprisecans end-connected by'resilient plastic (31 or 33); but the blade rootscomprise tube-flattened, hub-plate-clamped portions of the strongtubular material that are very flexible, permitting the blades toautomatically pivot with respect tov the rotors axis, thus balancing thetwo sides of the rotor under varying conditions of blade attack. In anautogyro or helicopter that is underway, for example, the stifflyresilient blades automatically flap up and down during each rotation.And in the form of the invention shown in FIGS. 19 and 15, the closelycompacted connections of the tubes of each blade to its rigid hingeplate 62' are sufficiently strong and flexible to counteract tendency ofthe blade to break off the hinge at its root.

Although the impeller hub of FIGS. 1 to 8 may be an integral part of therotary shaft, it is preferably a separate element, welded, bolted orotherwise fixed to the shaft. This hub is shown in FIGS. 1, 4 and 8 ascomprising a thick, metal plate 6, welded at 6' to the shaft 5 andpreferably bolted to the shaft with a bolt or bolts as in FIG. 4. Theedge of this plate is preferably arcuate; its curves are shown in FIG. 1as having a plurality of centers of curvature; but optionally it may becircular. In FIG. 7 the hub is indicated as comprising: a metal plate,preferably of steel, fixed to the shaft (like 6); four metal projections16, jutting upward or outward (toward the flattened-tube,impeller-support plies that are housed between the projections), theseprojections being of the proper height (extension from the hub plate 6)to allow the clamping plate 20 to be boltdrawn against them and alsosufficiently drawn against the flexible flattened-tube portions to clampthem tightly and sealingly between the plates 16 and 20; and fouroptional, hub-bracing bars, 18, that are welded to the shaft and to theshaftward surface of the hub plate.

A plurality of relatively-small-diameter hingeproviding tubular elementsare indicated as the main impeller-blade-supporting tubes in FIGS. 1 to8. In FIGS. 1 to 4 four such tubular elements are shown in each blade.Each aligned pair of these elements are the blade portions of anintegral, tubular member which extends from the tip of one blade overthe hub and to the tip of the opposite blade. Sectional FIG. 4illustrated one integral tubular member at 9-9 and four other integraltubular members having tube-flattened hinge portions at 9 that areorthogonally arranged relative to the member 9, as well as to the threeother members 9 that are not shown in FIG. 4 but are indicated in FIGS.1 to 3. The middle portions of all the tubular members 9 and 9 aretightly and flatly held on the hub plate 6 by clamping means which, asshown, is in the form of a plate, 20, screwed tightly down on the middletubular-member portions and the hub by means of the bolts 21 and nuts22.

As shown in FIG. 4, these tubular-member middle portionsaretightly-pressed tube folds, and the orthogonal arrangement of themembers is such that the middle folds of 9' fit over the middle folds of9. But optionally the middle portions of 9' may be slit sufficiently attheir sides for the four middlefolds of 9 to fit between the slit-formedplies of 9; and in this event all the axes of the blade-supportingtubular members 9 and 9' are in the same plane instead of in slightlyspaced planes as in FIG. 4.

In addition to its hub-attached, flat, flexible, hingeproviding fold orpair of slit plies, each of these hingeproviding, blade-supportingtubular members comprises: an arcuate-in-cross-section middle-bladepart, containing gaseous material; and a pair of flattenedtube,blade-tip portions, 24, each of which comprises flattened-tube end edgesthat are permanently sealed together by bonding material (for example,vulcanized rubber, epoxy putty or other plastic glue, brazing, weldingor solder).

The wall material of these members is of a type that will stand frequentand long-repeated flexing, especially at the integral, hubward hinges,without fracture or other disruption. This material optionally may be:cloth or metal fabric, impregnated and coated with resilient rubber orother flexible plastic; dense, strong, resilient plastic; thin sheetmetal that is very ductile or resilient (for example, thin copper oraluminum sheet, thin spring steel or phosphor-bronze or very thin lead),preferably covered with a flexible coating (for instance, rubberizedfabric or resilient plastic). The inventor currently prefers a sealed,thin-lead inner tube, permanently inflated, sheathed in aclosely-fitting envelope of strong, flexible fabric. Thin lead hasnumerous critical advantages in such tubes, for it may be flexedindefinitely a multitude of times without gas-losing fracture, withoutnecessity of subsequent re-inflation, and easily welded by simpleapplication of heat.

Each of the tubular members 9 and 9', as well as each of the othertubular members shown in FIGS. 5 to 18, contains gaseous materialpreferably helium, air or other gas preferably under high pressure (forexample, in the range of ten to thirty pounds per square inch); butoptionally this gaseous material may be gascell-containing foam plastic,preferably of the known pressurized type, as indicated in FIGS. 3 and 14at 26. When the gaseous material is pressurized gas it optionally may beforced into the tubular elements either thru a small, permanentlysealable, gas-inlet tube or a gasinlet valve. When the wall material ofthe tubular elements is permeable to gas (for example, of fabric andrubber) the gas preferably is intermittently supplied thru gas-inletvalves, indicated in FIG. at 27.

The airfoil-body material that is between the skin 8 and the tubularmembers 9 and 9 comprises: plastic (preferably foam plastic, optionallyresilient or substantially rigid, the liquid materials of whichoptionally may contain known fire-proofing chemicals); and optionallyand preferably other, blade-strengthening tubular members 10 and/or 12are imbedded in this airfoil-body plastic. The members 12 may beelongated or short metal cans, but preferably each is an elongated,hollow, corrugated, gas-containing element of the type shown in FIG. 13of bamboo or of mold-formed, dense plastic that has annular corrugationridges, 28. The tubular members 10 also may be of such bamboo or plastic(of diameters larger than 12); but preferably these are of any of thetypes shown in FIGS. 10 to 12, 14 and 16 to 19.

Each of these members 10 may be a single, elongated can of thin metal orstrong, dense plastic, extending nearly .the full length of a blade(optionally with flattened and sealed ends of the above-described typeor with disk-like ends); or, as shown in FIGS. 10, 11,17 and 18, eachmember 10 may be an end-joined row of cans, which may be of thin steelor aluminum or dense plastic. In any event, each member contains gaseousmaterial of the above-described type (gas, preferably pressurized, orfoam plastic). FIG. 10 shows end-joined cans of different diameters,with the end caps of cans of smaller diameter (30) being fixed bybonding-material, 31, of the above-described type (optionally resilientrubber) within the recessed end caps of largerdiameter cans, 32. FIG. 11shows similarly bondedtogether cans; here the can-end caps are notindented;

but they are fastened together by bonding material 33 that is similar to31. FIG. 12 shows a can, 34, having corrugated walls comprisingelongated corrugation ridges and grooves. This tubular element, whichmay be an integrally elongated tubular member, or a shorter can in a rowof end-joined cans, may be of aluminumalloy sheet of the type commonlysold as corrugated roofing (but preferably of thinner metal), made bybending the sheet around a mandrel and joining its edges by the weldingor other bonding material, 36. The annularly corrugated tube 38 of FIG.14 is of cast material, preferably of dense, strong, molded plastic. Anyof these tubular elements optionally may be made of blow-molded plastic.

The type of impeller shown in FIG. 7, somewhat similar to that of FIG.1, may have two or three blades; but as shown it has four. It comprisesintegral-hinge, bladesupporting, different-in-diameter, tubular members40 and 41, of materials and construction very similar to those of thetubes 9 and 9 of FIGS. 1 to 4; but the tubular members 40 and 41 areexampled as not integrally extending from one blade tip across the hubto an opposite blade tip. Instead, each has: a flattened-tube blade-tipportion, like the bands of material 24 of FIG. 1; an arcuatemiddle-of-the-blade portion; and a flattened-tube hubward portion thatextends across the hub plate 6 and ends in a line substantiallycoextensive with an edge of the hub plate. As above described, theoverlapping flattened-tube portions, compositely sheathed by thepreferable fabric-and-resilieat-plastic airfoil skin, are tightlyclamped between plates 6 and 20.

The flattened-tube portions are formed, at each end of the tubularmember, by flattening and thoroughly, sealingly bonding together the twocontiguous flat plies, so that the middle part of the tube, preferablycontaining highly pressurized gas (but optionally instead containinggas-cell-containing foam plastic preferably pressurized) remains arcuatein cross section, and from a point spaced from each flat end of thetubular member, toward each flat part, the curved tubular wallsarcuately flare outward on two sides and arcuately flare inward on twoother,.orthogonally located sides.

This inventor has discovered the following valuable inventive principlesin such flat-ended tubular elements: (1) They may be of thin, dense,impermeableto-gas material that is prone to damage by wrinkling, and yetbe easily, strongly and permanently inflated without wrinkling bylighter-than-air gas. For instance, this material may be very thin lead,copper, steel or other very thin metal or dense, permanentlywrinkleableplastic. Previously such inflation required the expensive andtime-consuming formation of a vacuum before inflation with helium or thelike, and this vacuum tried to flatten but badly wrinkled the denseparts and is substantially equal to l.57 times the circumference of thecross-sectional circle of the arcuate middle portion when the tubularmember is sufficiently long for this portion to taper from the flat endsthru blong cross sections to such a circle; and the length of each taperhas been roughly, empirically determined to be over 2% times suchdiameter. (2) When the band of the two bonded flat-end portions issufficiently extensive along the tubes axis, attachment bolts of thetype shown in FIG. 4 (at 21) or in FIG. 8 may be passed thru holes inthe flat, sealed portions.

When the flattened-end tubes of any of the illustrated propeller formsare of water-hose-like or rubber-tirelike materials, permeable to gas,they are provided with the gas-inlet valves 27, like those of rubbertires, thru which they may be repeatedly inflated with helium, air orother gas preferably to high pressure, for example of ten to thirtypounds per square inch. Examples of such permeable materials comprisevarious types of rubber-coated fabric (fiberglass, nylon or other cloth,or fine-wire mesh of spring steel, copper, aluminum alloy, or the like).

As illustrated in FIG. 8, the flared wall portions of a smaller tubularelement 41 are flattened to the same plane at 42, and the similar flaredwall portions of the opposite larger, propeller-leading-edge tube 40would taper to the same plane if, as is optional, the flattened portionsof the two tubular elements stopped and met at the line thru the axis ofthe hub plate 6 (and thru the axis of the impeller shaft that later inthe manufacture is welded to plate 6). But as shown the bonded flattenedportions 43 of the trailing-edge tube 41 extend thru and are stronglyglued to the overlying flattened portions 44 (folded and slit at thefolded edges) of the leading-edge tube 40. The similar overlapping andglued-together four flat plies of the pair of blade tubular elementsthat are orthogonally arranged with respect to tubes 40 and 41 are shownat 45 (plies of the smaller trailing-edge tube that have been widened byoverlying and tube-strengthening bands of glued or welded fabric) and 46(overlying flat plies of the larger tube). The leading-edge tube 40 ofthe left-hand set of tubes in FIG. 8 (not shown in section) isillustrated at 47. The smaller right-hand tube whose flattened ends areglued within those of tubular-member ends 47 is not seen in FIG. 8; butin FIG. 7 two such orthogonally arranged pairs are shown.

The hinge line between the hub and the flexible, blade-root,tube-flattened portions (and of the hubward flexible-skin element thatenvelops them) is determined by bordering edges of the clamping plate(20 or 20'). In FIGS. 1 and 4 this plate is square and these borderingedges (48) are normal to the axes of the blades. In FIGS. and 6 theplate 20' is shaped to provide straight portions 49 of its border, eachof which is in a plane making an oblique angle with the axis of itsadjacent blade. When the blade is in a vertical-axis impeller, isrotating in the direction of the arrow A, and momentarily moving againstfluid current, this oblique angle permits it to decrease its angle ofattack relative to the fluid current; and thus, against centrifugalforce, it balances the thrust of the blade that is opposite to its. Theborder of the plate 20 comprises edges that are angled to the edgeportions 49. Both of the plates 20 and 20 are preferably streamlined,with thin edges all around, as at 49A.

Instead of integrally flexible hinges for the tubular blades, metallic,pintle-comprising hinges, such as are indicated in FIGS. 15, 17 and 19,may be utilized. In FIGS. 15 and 16: the tubular members 50 are bisectedby a common plane 52 that in a lifting propeller is inclined to thehorizontal; the tubular member 54 is bisected by the inclined plane 55;but the axis of the hinge pintle is not thus inclined. Instead it ishorizontal, and is in or nearly in the horizontal plane indicated by theline 56 or in arrangement as in FIG. 9 the plane indicated at 56A. Thisline also indicates the top edge of the hinge plate 62 (or 62) that isfastened to ends of the cans 50 and 54 by the bolts 57. Each of thesetubular members 50 and 54 may be a single can (optionally having eitherdisk-like or flattened-tube ends) extending from points at or near thehub to points at or near the blade tip; or each member may be anendconnected row of shorter cans of the type shown in FIG. 17.

The blade hinges illustrated in FIGS. 15, 17 and 19 may be of aluminumalloy, stainless steel or other strong metal. As shown in FIGS. 17 and19, each of these hinges has: a plate 58, securely fixed to the metalhub 60 by bolts or rivets 61; another plate, 62 (62' in FIG. 19), thatis pivoted with respect to 58, fixed to can-end caps by the bolts 57 andnuts 63, and, as indicated at 62L, extends from the pintle to the thrustsurface of the blade; and the hinge pintle 64, forming part of the pivotbearing of the hinge. The plate 62 is securely fastened to the skin andtubular members of the propeller blade (or vane), 66, which may have anyof the forms to tubular members shown in FIGS. 9 to 19. When they havedisk-like hubward ends, the hingeattachment bolts 57 may be either fixedto each can end-cap before this cap is bonded to the can cylinder; orthey may be placed thru holes 67 after the end-cap is thus bonded. Inthis latter event the bolt heads preferably are located inside the can.

As indicated in FIGS. 9 and 16, the blade comprises a plurality ofjuxtaposed rows of tubular members; and as illustrated in FIG. 17, eachtubular member comprises a row of end-joined tubular cans 68 of the samediameter. The varying diameters of the rows (50 and 54 in FIG. 16) arepreferably calculated to fit closely within the aerodynamicallystreamlined plastic skin 70. As indicated in FIG. 17 at 71, the lowersurface of this skin 70 is coextensive with the lower edge of the hingeplate 61-62L. When relatively short, disk-ended cans of the type of 68are used, they preferably are of the general type (of thin sheet steel,aluminum or aluminum alloy) currently made by can-manufacturingcompanies and commonly used for holding food, liquids or othermaterials. Optionally the tubular containers may be filled with foamedplastic, which may be of the closed-gas-cell type; but preferably theycontain sealed gas (for example, air, helium, nitrogen, ammonia, orhydrogen mixed with a small amount of combustioninhibiting gas). Thisgas may be under pressure well above that of the atmosphere, placed inthe can thru an opening (or openings) in it, and then the opening issealed, preferably around a valve, stopper or other closure, with theaid of brazing, welding, solder, or epoxy putty or glue. The cans may beof the type commonly made with soldered end caps, or, like paint cans,with lids that snap into a recess; but such recess-filling lids arepreferably epoxy-glued, welded or soldered around their annular edges.

As indicated in FIG. 17, a layer of plastic or the like, 72, preferablystiffly resilient, is placed between adjacent ends of the cans. Thisoptionally may be plastic set from liquid materials poured in place, oran annular disk of sheet rubber that is glued to one or both of the canends.

The impeller blade of FIG. 19 is also optionally resilient orsubstantially rigid; but it is preferably stiffly resilient. In thisform the blades, having flattened-tube ends, are similar to those ofFIGS. 7 and 8 in optional wall materials, general method of constructionand the gaseous material they contain. But in FIG. 19 the flattenedhubward ends of the tubular members and the enveloping airfoil skin areshown as extending along upright planes instead of in the horizontalarrangement of such flattened ends in FIGS. 7 and 8. At the root of eachblade the flattened and sealed end of each of the tubular members isformed (bent, pressed or dieformed to the side) in a right angle to theaxis of the tube. When it is made of thin resilient metal its flathubward end is annealed before it is thus shaped; and when the tubecomprises thermoplastic material its hubward end is sufficiently heatedto plasticize it just before that end is formed into thehinge-attaching, tube-bracing angle.

The flange or brace 74 thus formed is securely fastened to the hingeplate 62, which is similar to plate 62 of FIG. 17. Epoxy glue or puttyis applied to the contiguous surfaces of the flanges 74 and plate 62,some of it penetrating holes 76 in the plate 62 and flanges 74 for extraholding power. And before this glue sets bolts of the general type of 57in FIG. 17, having screwdriver kerfs like those in the heads of bolts 21of FIG. 4, are extended thru the holes 76, and with a screwdriver in theexterior kerfs nuts like 63 of FIG. 17 are tightened. Preferably alsodense, strong plastic, 77 for example epoxy putty is applied between thehubward flattened portions at the time of assembly of the tubularmembers and hinge plate.

The impeller blade of FIG. 18 is also optionally either resilient orsubstantially rigid. Except for its lack of a pintle-comprising hinge itis of the same type of construction as the propeller of FIG. 17. Itselements 72 optionally may be resilient or substantially rigid plastic(for example, rubber or epoxy), and optionally may be only between thecans of each row or a row-spanning, resilient or substantially rigid ribof one of the abovedescribed types. When the blade is resilient (becauseof the resilient nature of 70 and 72), the impellers resiliency may beincreased by placing resilient elements similar to 72 between each bladeroot and the hub 60. The blade as a whole thus is optionally resilient,thus reducing damaging vibration and the possibility of breakage.

Each blade of FIG. 17 or FIG. 18 is completed by forming the optionallyflexible skin 70 (of fabricreinforced plastic, thin-copper, resilientsteel or other sheet metal) and placing plastic (preferably resilientfoam plastic) between the skin and tubular members.

The skin may be made by wrapping and flexible cement-gluing textile ormetallic fabric or mesh around the cans. Optionally this mesh may be offine-wire spring steel, fine-wire copper network, aluminum mesh orcloth. Preferably it is impregnated and glued, by flexible,liquid-rubber cement (for example, Pliobond) to an outer sheet ofresilient rubber before the composite skin is wrapped and glued to thecans and ribs. But

optionally the mesh may be first wrapped and flexibly glued to the cansand ribs, and then either sheet rubber is slightly stretched andflexibly-glued around the mesh or the blade frame is placed in ablade-shaping mold and liquid plastic materials (preferably mixed withfiberglas or other plastic-reinforcing elements) are poured into themold, around the frame. These materi- 1 als optionally may be the typewhich forms foamed plastic. This general method of molding may be usedin formation of any of the blades of FIGS. 1 to 19.

If the blade in any of the forms of the invented impeller is not thusfinished in a mold, its skin (optionally of reinforced plastic or of twoforged parts of sheet metal that are brazed or otherwise edge-bondedaround the tubular members) is drilled or punctured sufficiently toinject foamed-plastic liquids into the spaces around the tubularelements and within the skin; and then the skin is quickly sealed againto prevent loss of the foaming, gas-pressurized liquids. This way ofproviding airfoilbody plastic (optionally foamed plastic) is preferablyutilized in finishing all the impeller blades of the disclosed forms ofthis invention; but when they are of the integral-hinge type of FIGS. 1to 8 their skins are either: (l) entirely flexible of strong, resilientor highly ductile material (for example, fabric, coated with resilientplastic, or thin resilient or very ductile metal); or (2) the skin ofeach blade proper is a composite of metal or plastic sheet enveloped byan overall flexible skin of the above type (which in the forms of FIGS.1 to 8 extends across the hub and provides integrally flexible hinges).Each of the airfoil skins of this invention may be of one of the abovetwo optional types of construction.

When the tubular members are of the type shown in FIG. 10 the foamingplastic materials easily pass from a single injection inlet to allspaces around the cans because of the differences in their diameters;and when the containers are of the type indicated in FIGS. 11, 17 and 18the end caps in practice project slightly outward from the can cylindersand the foaming plastic also may be put in place thru one hole; butotherwise unless the blade is finished in a mold a plurality of inletholes are advisable.

In the following claims, unless otherwise qualified: the term tubularmember signifies a single, elongated can or tube of any cross-sectionalshape or a plurality of end-connected cans or tubes; can means a tubulararticle of any cross-sectional shape, comprising a middle hollowportion; tube signifies an elongated hollow article of anycross-sectional shape; tubular element means a single tube or candistinct from other tubular articles or a single tubular unit in atubular member as above defined; gaseous material means: any gas,gaseous mixture, gas-cell-containing foam plastic or yieldable materialcomprising fibers or other particles and air or other gas between theparticles; "gas": any pure gas, or mixture of gases (for example, air,or hydrogen mixed with inert gas); plastic: rubber or any other naturalor synthetic plastic; fabric: any fibrous or metallic cloth or mesh; andskin means: an exterior surface of material (for example of molded orcast material), an exterior coating, or an exterior sheath or envelope.

I claim:

1. A rotary impeller, comprising: a rotary shaft; blades connected tosaid shaft, each of which has a free end, unattached to other structure;and hinge means,

comprising blade-root-attachment means, connecting said blades to theshaft, permitting angular movement of each blade with respect to saidshaft in balancing said impeller during its rotary interaction with afluid current; in which:

each of the said blades comprises: an aerodynamically streamlined skin;within said skin, at least one elongated, sealed, inflated tube, having:curved wall structure, comprising dense, flexible material that issubstantially impermeable to gas; a bladeroot portion, adjacent to saidblade-rootattachment means, that comprises a pair of substantiallyflattened tube parts, integral with a middle portion of said tube, eachof said flattened parts being wider than an adjacent portion of thetubes middle part; means holding said substantially flattened tube partstogether in strong junction; gaseous material under above-atmosphericpressure in said sealed tube; and plastic between said skin and tube;and

the said hinge means further comprises means strongly fastening saidblade-root portions to said blade-attachment means, holding asubstantially flat surface of each blade-root portion in substantiallycompressed relation to the blade-attachment means.

2. An impeller as set forth in claim 1, in which: each of the said tubescomprises, adjacent to said free bladeend, a second pair of saidsubstantially flattened tube parts and means holding said last-namedtube parts together in strong, sealed junction.

3. An impeller as set forth in claim 1, in which said dense materialcomprises metal having ductility at least equal to that of copper.

4. An impeller as set forth in claim 3, in which said metal is lead.

5. An impeller as set forth in claim 1, in which said dense materialcomprises thin lead and a covering on the lead comprising fabric.

6. An impeller as set forth in claim 1, in which: said dense materialcomprises metal having ductility at least equal to that of copper; saidgaseous material comprises gas under above-atmospheric pressure, permanently sealed in each of said tubes; and each of said tubes comprises apermanently sealed inflation-gas inlet.

7. An impeller as set forth in claim 1, in which said gaseous materialis gas under pressure of at least 8 pounds per square inch, and each ofsaid tubes extends from a point near said shaft to an outer end adjacentto the tip of its blade and, at said outer end, comprises: a second pairof substantially flattened tube parts, each of which is wider than anadjacent portion of the tubes middle part; and means holding said secondpair of tube parts together in strong junction; whereby the said tubemay be temporarily changed in shape under external major shock andthereafter may return to its former configuration.

8. An impeller as set forth in claim 1, in which the said hinge meanscomprises: a hub plate, fixed to an end of said rotary shaft; integralextensions of said pair of substantially flattened tube parts, lying onand fixed to said hub plate; a clamping plate, juxtaposed to saidextensions on their side opposite to said hub plate; and in which thesaid blade-root-attachment means comprises rod-like clamping elements,tightly clamping together said clamping plate and tube-part extensionsand hub plate, whereby each of said blades may change its angle to theaxis of said shaft by bending of said flexible material in the integraljunction of said clamped extensions and blade-root portion.

9. An impeller as set forth in claim 1, comprising, in each blade, aplurality of juxtaposed tubes of the type of said elongated, inflatedtube, in which the said hinge means comprises: a hinge plate; integralextensions of each of said pairs of substantially flattened tube parts,in contact with said hinge plate, each of said pairs being turned atsaid plate to form an angle to the axis of its associated tube that isin the neighborhood of the said blade-root-attachment means, comprisingmeans securely fastening said extensions to said hinge plate; and apivot bearing providing for hinging motion of each of said blades withrespect to said shaft.

10. A rotary impeller, adapted to operate in a fluid, comprising: arotary shaft; blades connected to said shaft, each of which has anairfoil-shaped contour and a free end that is unattached to otherstructure; and hinge means, connecting said blades to said shaft,permitting angular movement of each blade with respect to the shaft inbalancing the centrifugal force and changing fluid-dynamic force on theblade during its rotation;

each of the said blades comprising a plurality of juxtaposed, sealed,inflated, elongated tubes, and each of the said tubes having: a curvedwall structure of blade-strength-providing flexible material;substantially flat blade-root and blade-tip portions, each portioncomprising a pair of integral, substantially flat tube parts, each ofwhich is wider than an adjacent portion of the tubes middle part; meansholding each pair of said substantially flat tube parts together instrong junction; gaseous material in each said sealed tube; tubularmembers, adjacent to said tubes, stiffening and strengthening saidblade; and plastic on and between said tubes and bladestiffeningmembers, having outer surfaces conforming to said airfoil-shapedcontour;

the said hinge means comprising: integral, hinge extensions of saidsubstantially flat blade-root portions; and blade-root-clamping means,fixed to said shaft, comprising a clamping element on each side of saidblade-root extensions and means forcing said elements and blade-rootextensions into tightly clamped relationship, securing said blades tosaid shaft.

11. An impeller as set forth in claim 10, comprising at least one pairof said blades, in which: the said pair of blades are on opposite sidesof the axis of said shaft; the said tubes are arranged in pairs, each ofsaid pairs of tubes having integral walland blade-root material,

and integrally-joined blade-root extensions between said clampingelements. i

12. An impeller as set forth in claim 10, in which said flexiblematerial comprises metal having ductility at least equal to that ofcopper.

13. An impeller as set forth in claim 12, in which said metal is lead.

14. An impeller as set forth in claim 10, in which said gaseous materialis gas.

15. An impeller as set forth in claim 14, in which said gas is underpressure above that of the atmosphere. 16. An impeller as set forth inclaim 10, in which said gaseous material is gas-cell-containing foamplastic.

17. An impeller as set forth in claim 10, in which said tubular memberscomprise metallic walls.

18. An impeller as set forth in claim 10, in which said tubular memberscomprise sealed cans.

19. An impeller as set forth in claim 18, in which each of said tubularmembers comprises a row of said cans in aligned, end-connectedarrangement.

20. An impeller as set forth in claim 19, in which said row comprisescans of relatively smaller diameter, endconnected to cans of relativelylarger diameter.

21. An impeller as set forth in claim 19, in which said cans arecorrugated.

22. An impeller as set forth in claim 10, in which at least some of saidtubular members comprise elongated blade-stiffening tubular elements,each of which has flattened-tube portions, one of said portions beingadjacent to said shaft, and the other comprising a said free end.

23. An impeller as set forth in claim 19, comprising bonding materialconnecting ends of end-connected pairs of the said cans.

24. An impeller as set forth in claim 10, in which the walls of saidtubular members have corrugations whose ridges and grooves aresubstantially parallel to longitudinal axes of tubular members.

25. An impeller as set forth in claim 10, in which the saidblade-stiffening tubular members comprise tubular elements havingcorrugations whose ridges and grooves extend around longitudinal axes oftubular members.

26. An impeller as set forth in claim 25, in which said tubular elementsare of bamboo.

27. An impeller as set forth in claim 1, in which said skin comprisesfabric and resilient plastic coating said fabric.

2. An impeller as set forth in claim 1, in which: each of the said tubescomprises, adjacent to said free blade-end, a second pair of saidsubstantially flattened tube parts and means holding said last-namedtube parts together in strong, sealed junction.
 3. An impeller as setforth in claim 1, in which said dense material comprises metal havingductility at least equal to that of copper.
 4. An impeller as set forthin claim 3, in which said metal is lead.
 5. An impeller as set forth inclaim 1, in which said dense material comprises thin lead and a coveringon the lead comprising fabric.
 6. An impeller as set forth in claim 1,in which: said dense material comprises metal having ductility at leastequal to that of copper; said gaseous material comprises gas underabove-atmospheric pressure, permanently sealed in each of said tubes;and each of said tubes comprises a permanently sealed inflation-gasinlet.
 7. An impeller as set forth in claim 1, in whiCh said gaseousmaterial is gas under pressure of at least 8 pounds per square inch, andeach of said tubes extends from a point near said shaft to an outer endadjacent to the tip of its blade and, at said outer end, comprises: asecond pair of substantially flattened tube parts, each of which iswider than an adjacent portion of the tube''s middle part; and meansholding said second pair of tube parts together in strong junction;whereby the said tube may be temporarily changed in shape under externalmajor shock and thereafter may return to its former configuration.
 8. Animpeller as set forth in claim 1, in which the said hinge meanscomprises: a hub plate, fixed to an end of said rotary shaft; integralextensions of said pair of substantially flattened tube parts, lying onand fixed to said hub plate; a clamping plate, juxtaposed to saidextensions on their side opposite to said hub plate; and in which thesaid blade-root-attachment means comprises rod-like clamping elements,tightly clamping together said clamping plate and tube-part extensionsand hub plate, whereby each of said blades may change its angle to theaxis of said shaft by bending of said flexible material in the integraljunction of said clamped extensions and blade-root portion.
 9. Animpeller as set forth in claim 1, comprising, in each blade, a pluralityof juxtaposed tubes of the type of said elongated, inflated tube, inwhich the said hinge means comprises: a hinge plate; integral extensionsof each of said pairs of substantially flattened tube parts, in contactwith said hinge plate, each of said pairs being turned at said plate toform an angle to the axis of its associated tube that is in theneighborhood of 90*; the said blade-root-attachment means, comprisingmeans securely fastening said extensions to said hinge plate; and apivot bearing providing for hinging motion of each of said blades withrespect to said shaft.
 10. A rotary impeller, adapted to operate in afluid, comprising: a rotary shaft; blades connected to said shaft, eachof which has an airfoil-shaped contour and a free end that is unattachedto other structure; and hinge means, connecting said blades to saidshaft, permitting angular movement of each blade with respect to theshaft in balancing the centrifugal force and changing fluid-dynamicforce on the blade during its rotation; each of the said bladescomprising a plurality of juxtaposed, sealed, inflated, elongated tubes,and each of the said tubes having: a curved wall structure ofblade-strength-providing flexible material; substantially flatblade-root and blade-tip portions, each portion comprising a pair ofintegral, substantially flat tube parts, each of which is wider than anadjacent portion of the tube''s middle part; means holding each pair ofsaid substantially flat tube parts together in strong junction; gaseousmaterial in each said sealed tube; tubular members, adjacent to saidtubes, stiffening and strengthening said blade; and plastic on andbetween said tubes and blade-stiffening members, having outer surfacesconforming to said airfoil-shaped contour; the said hinge meanscomprising: integral, hinge extensions of said substantially flatblade-root portions; and blade-root-clamping means, fixed to said shaft,comprising a clamping element on each side of said blade-root extensionsand means forcing said elements and blade-root extensions into tightlyclamped relationship, securing said blades to said shaft.
 11. Animpeller as set forth in claim 10, comprising at least one pair of saidblades, in which: the said pair of blades are on opposite sides of theaxis of said shaft; the said tubes are arranged in pairs, each of saidpairs of tubes having integral wall and blade-root material, andintegrally-joined blade-root extensions between said clamping elements.12. An impeller as set forth in claim 10, in which said flexiblematerial comprises metal having ductility at least equal to that ofcopper.
 13. An impeller as set forth in claim 12, in which said metal islead.
 14. An impeller as set forth in claim 10, in which said gaseousmaterial is gas.
 15. An impeller as set forth in claim 14, in which saidgas is under pressure above that of the atmosphere.
 16. An impeller asset forth in claim 10, in which said gaseous material isgas-cell-containing foam plastic.
 17. An impeller as set forth in claim10, in which said tubular members comprise metallic walls.
 18. Animpeller as set forth in claim 10, in which said tubular memberscomprise sealed cans.
 19. An impeller as set forth in claim 18, in whicheach of said tubular members comprises a row of said cans in aligned,end-connected arrangement.
 20. An impeller as set forth in claim 19, inwhich said row comprises cans of relatively smaller diameter,end-connected to cans of relatively larger diameter.
 21. An impeller asset forth in claim 19, in which said cans are corrugated.
 22. Animpeller as set forth in claim 10, in which at least some of saidtubular members comprise elongated blade-stiffening tubular elements,each of which has flattened-tube portions, one of said portions beingadjacent to said shaft, and the other comprising a said free end.
 23. Animpeller as set forth in claim 19, comprising bonding materialconnecting ends of end-connected pairs of the said cans.
 24. An impelleras set forth in claim 10, in which the walls of said tubular membershave corrugations whose ridges and grooves are substantially parallel tolongitudinal axes of tubular members.
 25. An impeller as set forth inclaim 10, in which the said blade-stiffening tubular members comprisetubular elements having corrugations whose ridges and grooves extendaround longitudinal axes of tubular members.
 26. An impeller as setforth in claim 25, in which said tubular elements are of bamboo.
 27. Animpeller as set forth in claim 1, in which said skin comprises fabricand resilient plastic coating said fabric.